The detection of a viroid in Coleus blumei species in Brazil (1) has prompted us to search for viroids in C. blumei cultivars (cvs) commercially propagated by cuttings for more than 50 years in Germany. 'Return' PAGE (2) of nucleic acid extracts from the cv 'Bienvenue' revealed a band of circular viroid-like RNA molecules. Northern blot analysis (3) with radioactive probes specific for viroids ...

A viroid-like disease causing mosaic leaves and dwarfism was found on mulberry plants in Zhejiang, China. Grafting of stems from infected plants onto healthy plants resulted in the same symptoms on the healthy plants. A circular small RNA (Mmd-v RNA1) was isolated from the infected plant leaves and caused identical symptoms after more than two years. Nucleotide sequencing indicated that the Mmd...

The sequence of the 356 nucleotide residues of chrysanthemum stunt viroid (CSV) has been determined. Overlapping linear viroid fragments were obtained by partial ribonuclease digestion, radiolabelled in vitro at their 5'-ends, and sequenced using partial enzymic cleavage methods. Of the CSV sequence, 69% is contained in the published sequence of potato spindle tuber viroid (PSTV). Differences i...

A commentary on Invasion of shoot apical meristems by Chrysanthemum stunt viroid differs among Argyranthemum cultivars Given that they do not encode proteins, viroid RNAs are extremely dependent on host factors for completing their infection cycle. This cycle consists of: (i) access to the organelle wherein they are replicated, the nucleus in the family Pospiviroidae (type member potato spindle...

In autumn 2006, a new disease was observed in a glasshouse-grown crop of sweet pepper (Capsicum annuum L.) in the Netherlands. Fruit size of the infected plants was reduced up to 50%, and plant growth was also slightly reduced. Here we show that the disease is caused by a previously non-described viroid. The pepper viroid is transmitted by both mechanical inoculation and pepper seeds and, when ...

Viroids are small, circular, single-stranded RNA molecules that, while not coding for any protein, cause several plant diseases. Viroids rely for their infectious cycle on host proteins, most of which are likely to be involved in endogenous RNA-mediated phenomena. Therefore, characterization of host factors interacting with the viroid may contribute to the elucidation of RNA-related pathways of...

The effect of carrageenans on tomato chlorotic dwarf viroid (TCDVd) replication and symptom expression was studied. Three-week-old tomato plants were spray-treated with iota(ɩ)-, lambda(λ)-, and kappa(κ)-carrageenan at 1 g·L-1 and inoculated with TCDVd after 48 h. The λ-carrageenan significantly suppressed viroid symptom expression after eight weeks of inoculation, only 28% plants showed distin...

A large body of evidence has lead to the suggestive proposal of a potential interplay between viroid-induced pathogenesis and RNA silencing regulatory mechanisms. A variety of techniques have been used to examine this interaction. This chapter outlines the use of a green fluorescent protein (GFP) sensor, containing viroid-specific sequence targets to study this phenomenon. In addition, a sympto...

The chrysanthemum (Dendranthema X grandiflorum) belongs to the family Asteraceae and it is one of the most popular flowers in the world. Viroids are the smallest known plant pathogens. They consist of a circular, single-stranded RNA, which does not encode a protein. Chrysanthemums are a common host for two different viroids, the Chrysanthemum stunt viroid (CSVd) and the Chrysanthemum chlorotic ...

Recent experience using 23 oligonucleotides to diagnose avocado sunblotch viroid (ASBV) is described. In a number of field collected samples with sunblotch symptoms, the probe was unsuccessful in detecting the viroid. The sunblotch viroid varies greatly from branch to branch in a tree. Tree to tree variation is also common. However, the probe can be used with a reasonable measure of success to ...